Dimitris M. Chatzigeorgiou

Analysis and design of an in-pipe system for water leak detection

In most cases the deleterious effects associated with the occurrence of leaks may present serious problems and therefore, leaks must be quickly detected, located and repaired. The problem of leakage becomes even more serious when it is concerned with the vital supply of fresh water to the community. In addition to waste of resources, contaminants may infiltrate into the water supply. The possibility of environmental health disasters due to delay in detection of water pipeline leaks has spurred research into the development of methods for pipeline leak and contamination detection. Leaking in water networks has been a very significant problem worldwide, especially in developing countries, where water is sparse. Many different techniques have been developed to detect leaks, either from the inside or from the outside of the pipe; each one of them with their advantages, complexities but also limitations. To overcome those limitations we focus our work on the development of an in-pipe-floating sensor. The present paper discusses the design considerations of a novel autonomous system for in-pipe water leak detection. The system is carefully designed to be minimally invasive to the flow within the pipe and thus not to affect the delicate leak signal. One of its characteristics is the controllable motion inside the pipe. The system is capable of pinpointing leaks in pipes while operating in real network conditions, i.e. pressurized pipes and high water flow rates, which are major challenges.Copyright

Node Localization in Robotic Sensor Networks for Pipeline Inspection

Robotic sensor networks provide an effective approach for underground pipeline inspection. Such networks are comprised of sensor nodes (SNs) and relay nodes (RNs) carried by robots for information sensing and communication, and are able to perform accurate and realtime inspection, especially in adverse environments. SN localization is critical in such networks because localization results can be used not only for locating and pinpointing leaks, but also for maneuvering mobile SNs in a pipeline of complex configuration. However, both the underground operational environment and the limited resources of the SNs pose significant challenges for SN localization. This paper presents algorithms for SN localization in robotic sensor networks for underground pipeline inspection. Specifically, self-localization of underground in-pipe SNs were investigated by taking into account SN movement dynamics, and using the measurements of the SNs velocity and the received signal strength (RSS) of the radio signal from aboveground RNs. Depending on the availability of the RSS at the SN, different localization algorithms based on the Kalman filter are proposed for different scenarios. Simulation results show the efficacy of the proposed algorithms. The framework also provides insight into the design of robotic sensor networks for the inspection and maintenance of other types of pipeline systems, such as oil and gas pipelines.

Design and analysis of novel friction controlling mechanism with minimal energy for in-pipe robot applications

In-pipe wheeled robots require friction on the wheels to maintain traction. Ability to vary this friction is highly desirable but conventionally used linkage mechanism is not suitable for it. This paper presents a novel mechanism generating adjustable friction with minimal energy consumption for in-pipe robots. The mechanism uses permanent magnets to achieve the objective. An appropriate model for the system is also presented and discussed. The paper identifies the important design parameters, and more importantly establishes the relation between the design parameters and the systems performance. In addition, a prototype of the mechanism was designed, fabricated and tested for validation.

AN IN-PIPE LEAK DETECTION SENSOR: SENSING CAPABILITIES AND EVALUATION

In most cases the deleterious effects associated with the occurrence of leak may present serious problems and therefore leaks must be quickly detected, located and repaired. The problem of leakage becomes even more serious when it is concerned with the vital supply of fresh water to the community. In addition to waste of resources, contaminants may infiltrate into the water supply. The possibility of environmental health disasters due to delay in detection of water pipeline leaks has spurred research into the development of methods for pipeline leak and contamination detection. Leaks in water pipes create acoustic emissions, which can be sensed to identify and localize leaks. Leak noise correlators and listening devices have been reported in the literature as successful approaches to leak detection but they have practical limitations in terms of cost, sensitivity, reliability and scalability. To overcome those limitations the development of an in-pipe traveling leak detection system is proposed. The development of such a system requires a clear understanding of acoustic signals generated from leaks and the study of the variation of those signals with different pipe loading conditions, leak sizes and surrounding media. This paper discusses those signals and evaluates the merits of an in-pipe-floating sensor.Copyright

Modeling and analysis of an in-pipe robotic leak detector

Leakage is the most important factor for unaccounted losses in any pipe network around the world. Most state of the art leak detection systems have limited applicability, lack in reliability and depend on user experience for data extraction. This paper is about a novel system for robotic pipe integrity inspection. Unlike existing systems, detection in based on the presence of a pressure gradient in the neighborhood of a leak. This phenomenon is translated into force measurements via a specially designed and instrumented mechanical embodiment (detector). In this paper an analytic dynamic model of the robotic detector is derived and studied. A prototype is built and the main concepts are validated via experiments.

Quantifying Acoustic and Pressure Sensing for In-Pipe Leak Detection

Experiments were carried out to study the effectiveness of using inside-pipe measurements for leak detection in plastic pipes. Acoustic and pressure signals due to simulated leaks, opened to air, are measured and studied for designing a detection system to be deployed inside water networks of 100 mm (4 inch) pipe size. Results showed that leaks as small as 2 l/min can be detected using both hydrophone and dynamic pressure transducer under low pipe flow rates. The ratio between pipe flow rate and leak flow rate seems to be more important than the absolute value of leak flow. Increasing this ratio resulted in diminishing and low frequency leak signals. Sensor location and directionality, with respect to the leak, are important in acquiring clean signal.Copyright

Design and Evaluation of an In-Pipe Leak Detection Sensing Technique Based on Force Transduction

Leakage is the major factor for unaccounted fluid losses in almost every pipe network. In most cases the deleterious effects associated with the occurrence of leaks may present serious economical and health problems and therefore, leaks must be quickly detected, located and repaired. The problem of leakage becomes even more serious when it is concerned with the vital supply of fresh water to the community. Leaking water pipelines can develop large health threats to people mostly because of the infiltration of contaminants into the water network. Such possibilities of environmental health disasters have spurred research into the development of methods for pipeline leakage detection.Most state of the art leak detection techniques have limited applicability, while some of them are not reliable enough and sometimes depend on user experience. Our goal in this work is to design and develop a reliable leak detection sensing system. The proposed technology utilizes the highly localized pressure gradient in the vicinity of a small opening due to leakage in a pressurized pipeline. In this paper we study this local phenomenon in detail and try to understand it with the help of numerical simulations in leaking pipelines (CFD studies). Finally a new system for leak detection is presented.The proposed system is designed in order to reduce the number of sensing elements required for detection. The main concept and detailed design are laid out. A prototype is fabricated and presented as a proof of concept. The prototype is tested in a simple experimental setup with artificial leakages for experimental evaluation. The sensing technique discussed in this work can be deployed in water, oil and gas pipelines without significant changes in the design, since the concepts remain the same in all cases.© 2012 ASME

Modeling and parameter estimation for in-pipe swimming robots

State-of-the-art, in-pipe, crawling robots face challenges in small diameter, non-smooth, water distribution pipes, mostly because of their direct contact with the pipe walls. On the other hand, swimming robots show greater potential in performing various maneuvers inside the pipes, because of the freedom in their motion. Such autonomous, swimming robots are needed for pipe-monitoring and leak detection in all sorts of pipe networks. Swimming motion inside confined environments is not well studied, and thus, this paper tackles the problem of modeling an in-pipe swimming vehicle. A conventional methodology that involved hydrodynamic coefficients is adopted, however the confined environment is affecting the parameters under study heavily. We discuss how these parameters rely on the pipe and robot geometry, unlike the case where the robot would swim in open-water.

MIT Leak Detector: Modeling and Analysis Toward Leak-Observability

Leakage is the most important factor for unaccounted losses in any pipe network around the world. However, most state-of-the-art leak detection systems have limited applicability, lack in reliability and depend on user experience for data interpretation. In addition, most of them are not scalable to the network level because inspection is slow. In this study, we present a new autonomous in-pipe leak sensing system; the “MIT leak detector.” We start by describing the fundamental concept behind detection, and present the proposed design. The detection principle in based on the presence of a pressure gradient in the neighborhood of any leak in a pressurized pipe. This phenomenon is translated into force measurements via a carefully designed and instrumented mechanical embodiment. In addition, an analytic dynamic model of the robotic detector is derived. Further study and analysis show that the proposed system can sense leaks at any angle around the circumference of the pipe by utilizing two force measurements at specific locations. Finally, a prototype is built and experiments are conducted in order validate the observability concepts discussed in this paper.

Detection & estimation algorithms for in-pipe leak detection

Leakage is the most important factor for unaccounted losses in any pipe network around the world. However, most state of the art leak detection systems have limited applicability, lack in reliability and/or depend on user experience for data interpretation. In this paper we present a new, autonomous, in-pipe, leak detection system. The detection principle is based on the presence of a pressure gradient in the neighborhood of a leak in a pressurized pipe. This phenomenon is translated into force measurements via a carefully designed and instrumented mechanical embodiment (MIT Leak Detector). We then introduce a detection and estimation scheme. The latter one allows not only for the reliable detection, but also for the estimation of the incidence angle and the magnitude of the forces that are associated with the leak. Finally, a prototype is built and experiments in pipes are conducted to demonstrate the efficacy of the proposed methodology.